The present invention relates to a method and an arrangement for transmitting data and for examining the transmission characteristics in a radio communications system.
In radio communications systems, data like signaling data, voice data or other user data are transmitted with the aid of electromagnetic waves via a radio interface between the transmitting and the receiving device, at least in a part-area of the communications system. An example of current radio communications networks are networks according to the GSM standard and with a TDMA transmission method which are operated at carrier frequencies of 900, 1800 or 1900 MHz. Another example are future radio communications systems such as UMTS which is based on a CDMA, TD/CDMA or TDD transmission method and uses carrier frequencies in the range of approx. 200 MHz. The data to be transmitted are transmitted at these carrier frequencies between base stations of the communications system at the network end and mobile or stationary terminals at the subscriber end.
Special radio communications systems are those which have a time slot structure. As a rule, the timeslots are combined in timeslot frames which, in turn, can be part of a higher-level frame structure. Examples of such radio communications systems with a timeslot structure are TDMA, TDD, TD/CDMA, TD/SDCDMA and FDD systems. In the case of a GSM system, for example, eight timeslots are combined in one timeslot frame. Each individual timeslot has a duration of 0.577 ms and the complete timeslot frame has a duration of about 4.6 ms.
In a TDD system in UMTS, in contrast, a timeslot frame has 16 timeslots which in each case have a duration of 625 μs. The complete timeslot frame has a duration of 10 ms. A part of the timeslots of a TDD timeslot frame is used for the uplink from the terminal at the subscriber end to the base station and the other part of the timeslots of the timeslot frame is used for the downlink from the base station to the terminal at the subscriber end. Between the timeslots of the uplink and the downlink, at least one switching point is inserted which can be shifted within the timeslot frame in order to provide for an asymmetric allocation of the timeslots to the uplink and to the downlink.
Within a timeslot, a data block or burst is transmitted with a particular predefined structure. Apart from payload data, the data block can also contain other data which are necessary or useful for the transmission of the payload data. Thus, for example, control or signaling data or particular measurement data such as, for example, for determining the transmission characteristics can be provided in these data blocks.
A major aim in radio communications systems is to provide the subscribers with the highest possible measure of comfort. In particular, the best possible quality of data transmission is to be guaranteed to the subscribers, on the one hand and, on the other hand, the highest possible data rate is to be provided by corresponding transmission capacity. These requirements represent an increasing problem especially with regard to the continuously growing numbers of subscribers in radio communications systems.